This circuit was found in a Popular Electronics from the 90s. It is based on components still common today and an optical coupler for the triac. The sensor is a thermistor.
This two-output circuit was found in General Electric documentation from the 1990s. The circuit uses...
This circuit was taken from Popular Electronics from May 1968. The circuit is sensitive with...
This circuit uses the 2N626, the first commercial Darlington transistor. We found it in Radio...